Drill grinder



c. L! GARRISON DRILL GRINDER April 9, 1963 I BY 3 V ATTORNEY;

Filed March 6, 1961 United States Patent 3,084,485 DRILL GRINDER Clifford L. Garrison, Adrian, Mich, assignor to player Instrument Company, Adrian, Mich, a corporation of Michigan Filed Mar. 6, 1961, Ser. No. 93,478 14 Claims. (Cl. 51124) This invention relates to apparatus for grinding and shaping the cutting edges or lips and relief clearance of drills and more especially to a drill grinder of a character particularly adaptable for grinding and shaping the points of medium and small size drills.

The present invention embraces an apparatus for grinding drills which requires a minimum of adjustments necessary to produce a drill point having desired cutting angles and relief clearance.

Another object of the invention is the provision of a drill grinder having adjustable cam means of variable pitch for regulating or controlling the amount of relief by varying the locus or path of traverse of the end region of the drill with respect to the grinding wheel.

Another object of the invention is the provision of a drill grinder wherein the drill is pre-set in a chuck or holder for establishing a predetermined relation of the drill to be sharpened with a variable pitch cam whereby varying degrees of relief clearance may be formed on the drill, the chuck being reversible whereby the cutting lips and relief areas on a dual fluted drill are of uniform character.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is a front elevational view of a grinding apparatus of the invention;

FIGURE 2 is a top plan view of the apparatus, certain parts being shown in section;

FIGURE 3 is a vertical sectional view taken substantially on the line 3-3 of FIGURE 2;

FIGURE 4 is a sectional view taken substantially on the line 44 of FIGURE 2;

FIGURE 5 is a detail plan view illustrating a gage means for pre-setting a drill in a chuck, the view being in the direction of line 55 of FIGURE 4;

FIGURE 6 is a detail sectional view taken substantially on the line 6-6 of FIGURE 4;

FIGURE 7 is a plan view of a portion of the apparatus illustrating the relative position of the drill and grinding wheel during grind operations;

FIGURE 8 is a detail sectional view taken substantially on the line 8-8 of FIGURE 7;

FIGURE 9 is a detail sectional view taken substantially on the line 9-9 of FIGURE 7;

FIGURE 10 is an isometric View illustrating the means and method of retaining the drill and chuck in a holder during grinding operations;

FIGURE 11 is a schematic view illustrating three different positions of contact of the drill point with the grinding wheel during a grinding operation;

FIGURE 12 is a schematic view illustrating the relation between the end of the drill and the grinding wheel and one of the positions indicated in FIGURE 11;

FIGURE 13 is a schematic view illustrating the relative position between the drill and the grinding wheel at a second position indicated in FIGURE 11;

FIGURE 14 is a view illustrating the relation between the drill and the grinding wheel at a third position indicated in FIGURE 11;

FIGURE 15 is an enlarged view of an end of a drill ground or shaped by the apparatus of the invention;

FIGURE 16 is a plan view of a variable pitch control cam forming a component of the construction;

FIGURE 17 is an elevational view of the cam illustrated in FIGURE 16, and

FIGURE 18 is an elevational view of the cam rotated through an angle of with respect to the position of the cam illustrated in FIGURE 17 The arrangement of the invention illustrated in the drawings is particularly adapted for grinding or pointing drills of comparatively small sizes, but it is to be understood that the principles of the invention and the method of grinding variable relief upon drills may be employed or adapted for grinding or imparting relief areas to other types of rotatable cutting tools Referring to the drawings in detail and initially to FIG- URES 1 through 4, the grinding apparatus is inclusive of a base or base frame 10 which is of comparatively thin walled hollow construction as illustrated in FIGURE 3, a driving motor 12, preferably of the electrically energizaable type, being contained within the housing 10. The motor 12 is supported upon a member or platform 14 which is pivotally mounted on a pin or shaft 16 extending through openings in boss portions formed integrally with the wall of the housing Iii, as shown in FIGURES l and 3.

' The pivot 18 is adjacent one edge region of the motor support member 14 whereby the weight of the motor 12 and platform 14 exerts constant tension upon a driving belt 20 engaging a drive pulley 21 mounted upon the motor shaft 22, as shown in FIGURES l and 3. The pivotal movement of the member 14 is restricted by means of a screw 24 mounted in a threaded opening formed in the wall of the housing 10. The housing 10 is provided with an upper horizontally arranged wall portion 26 to which is secured a member 28 having convergently arranged surfaces 30 extending lengthwise of the apparatus.

Mounted upon the upper surface of the housing portion 26 is a carriage 32 movable lengthwise of the member or tang 28, an adjustable gib 31 provided adjacent one of the angular surfaces 30 being adjustable to compensate for wear of the guiding surfaces. Secured to the forward portion of the carriage 32 is a fitting 34 accommodating an externally threaded bushing 35 which surrounds a tenon 36 formed on a lead screw 40 provided with a collar 37. A handle 38 secured to the bushing 35 provides means for readily moving the carriage 32 relative to the lead screw 40 to withdraw the drill a slight distance away from the grinding wheel to reverse the drill during grinding operations, the handle 38 normally engaging a stop or abutment pin 39.

The tang 28 is provided with a bore 42 accommodating the lead screw 40, an internally threaded sleeve 44 being pressed into the bore 42, the sleeve having threaded connection with the lead screw 40 whereby rotation of the lead screw adjusts the carriage 32 lengthwise of the tang 28. Fixed on the tenon 36 is a knurled manipulating knob 45 for rotating the lead screw 40.

Mounted upon the carriage 32 is a second carriage or' crosshead 52 formed with a tang portion 53 which is mounted in a dovetail shaped recess 51 formed in the carriage, 32 as shown in FIGURE 3, the crosshead or second carriage 52 being movable along an axis at right angles or normal to the axis of adjustment of the car riage 32.

The tang portion 52 is secured to the second carriage or crosshead 50 by screws 54, shown in FIGURE 4. The tang 53 is provided at its outer end with a fitting 56 which is bored to accommodate a tenon portion 58 of a lead 17) screw 60 extending into and cooperating with a threaded bore 62 formed in the carriage 32.

A knurled knob 64 is secured to the tenon 58 of the lead screw 60 for rotating the lead screw to adjust the second carriage or crosshead 52 in a direction transversely of the carriage 32. A gib 66 is arranged at one side of the tang 53, as shown in FIGURE 3, and may be drawn into a position to clamp the tang 53 in adjusted position by means of a knurled headed bolt 67 shown in FIGURE 3.

With particular reference to FIGURE 2, a generally cylindrically-shaped casing 70 is integrally formed with the base through a connecting portion 71 and reinforcing ribs 72. The casing 7b is of hollow configuration and the interior end regions thereof are bored to accommodate ball bearings 74 or other anti-friction bearings in which is rotatably journaled an arbor or shaft 76. The arbor or shaft 76 is formed at its forward end with a tenon 78 upon which is secured a cup-shaped grinding wheel 80 which is held in place by disc or washer 79 and a threaded nut 81 cooperating with a threaded portion formed on the tenon 7 8.

A grinding wheel guard 82 secured to the casing '76 partially surrounds the grinding wheel as shown in F1 URES 1 and 2. The opposite end region of the shaft or arbor 76 is provided with a tenon portion 84 to which is keyed a pulley 86 driven by the belt 20, a nut 87 threaded upon a tenon portion of the shaft to secure the pulley on the tenon 84. A cover plate 89 secured to the housing 10 by means of screws 90 encloses the pulleys 12 and 86 and the driving belt 20 in the manner shown in FIGURES 2 and 3.

The arrangement is inclusive of a means for dressing or truing the grinding face 92 of the cup-shaped grinding wheel 80. As shown in FIGURES l and 2, the member or carriage 32 is formed with space projecting bosses 94 which are bored to accommodate a stub shaft 95. Journaled for rotation upon the shaft 95 is a member 97 formed with an angularly projecting arm 98 terminating in a handle portion 99 for swinging the member 97 about the axis of the shaft 95. The handle portion 99 is provided with a boss 160 in Which is secured a truing diamond 102, which is adapted when the handle 99 is moved up wardly, as viewed in FIGURE 1, to move the truing diamond 102 across the grinding face 92 of the wheel to dress or true the wheel face.

The apparatus of the invention is constructed and arranged whereby during the grinding operation of a drill, the drill is oscillated about an axis and is simultaneously movable lengthwise of the axis of oscillation under the influence of a cam to grind a cutting edge or lip and to provide relief clearance on the drill. The amount or angularity of relief imparted to a drill is controlled through a variable pitch cam and roller arrangement here inafter described.

The crosshead or secondary carriage 52 mounted on the carriage 32 is integrally formed with a generally cylindrically shaped housing 106. Disposed within the cylindrically shaped housing 1136 is a shaft N8 which is mounted in suitable ball bearings 11d and 112 contained respectively Within sleeves 114 and 116, the sleeves being pressed into the cylindrical housing 1636. Mounted upon the shaft 108 is an abutment or collar 118 which is held upon the shaft by means of a setscrew 119. Surrounding the shaft 108 and engaging the end of sleeve 116 is a second collar 120. Disposed between the collars 118 and 120 is an expansive coil spring 122 which normally biases or urges the shaft 193 in a left-hand direction, as viewed in FIGURE 4.

The housing 106 is provided with a cylindrical surface 124 which supports a generally cup-shaped member 126 having a closed end 127, as shown in FIGURE 4. Disposed within the cup-shaped housing 126 is a cam member or block 129 having a central bore accommodating the end region of shaft 198. The cam member 129 is formed with a cam surface 131 of variable pitch as illus- 8 trated in FIGURES 16 through 18. The cam member 129 is secured to the housing 126 by a screw 132 extending through a boss portion on the housing 126 into a threaded opening 133 in the cam block.

The right-hand end region of shaft 108, as viewed in FIGURE 4, has a transverse bore accommodating a pin or shaft 136 which extends exteriorly of shaft 168 and journally supports a cam follower or roller 138. The pin 136 is secured to the shaft 108 by a setscrew 139.

The housing 126 is formed with an upwardly extending portion 140 shaped with projections 142 and 144 at each side of a space 145 as particularly shown in FIGURE 5. Secured to the projections r142 by screws 143 is a gage block 147.

The gage block 147 is provided with an angular or oblique gaging surface 1511 providing a means for presetting a drill in a chuck construction 152 adapted to be mounted in a supporting fixture 154. The chuck and drill are subsequently transferred to a holder for carrying on grinding operations. Pressed into an opening formed in the cylindrical member 1136 is a pin 156 which projects into the space 145 provided between the projections 142 and 144. The housing 126 is rotatable about the cylindrical surface 124 of the cylindrical member 1416 to the extent permitted by the projections 142 and 144 on the portion 140 limiting the movement of the housing 126.

Means is provided for locking the cup-shaped housing 126 in various positions of adjustment. As shown in F-EGURE 4, the portion 141 of housing 126 is provided with a threaded opening accommodating a locking screw 158 provided with a knurled knob 16% for manipulation of the locking screw 158, the end of the screw engaging the cylindrical surface 124 of the housing 106. As the cam block 129 is secured to the cup-shaped member 126, the cam block position may be changed by adjusting the relative position of the housing 126 with respect to the shaft 108 and the cam follower or roller 13-8.

Formed on the left-hand end of shaft 1113, as viewed in FIGURE 4, is a tenon 162 on which is fixedly secured a member 164- integrally provided with an arcuately shaped portion 166, shown in FIGURES 2 and 7, formed with an arcuately shaped recess 167. The arcuately shaped recess .167 snugly, yet slidably, accommodates an arcuately shaped member or sector 17%. The sector 17% is maintained in the recess 167 by means of a cover plate 172, shown in FIGURE 4, secured to member 16 by screws 173.

Secured to the member 164 is a cylindrically shaped dust shield 174 which is slidable within a sleeve 176 secured to the cylindrical housing 106, as shown in FIGURE 4. It should be noted that the flange portion of the dust shield 174 is spaced from the end of the cylindrical member 106 so as to facilitate longitudinal slidable movement of the shaft 108 lengthwise of the member 106 under the influence of the cam follower 138 cooperating with the variable pitch earn surface 133 of the cam block 129.

The sector shaped portion .166 of member 1 64 is provided with a threaded opening receiving a setscrew or clamping screw 178 for locking the sector in an arcuately adjusted position with respect to the member 166. As shown in FIGURE 7, the sector 17% is provided with graduations 179 which cooperate with an edge 180' on member 166 as an index or indicator. Through the arcuate adjustment of the sector 1711 with respect to member 166, the drill to be ground may be set at a desired angle for the cutting edges or lips of the drill. The sector 171 is provided with a drill chuck holder 134 hereinafter described in detail.

The drill D to be ground is mounted in a suitable chuck 152 which is received in the gaging fixture 154 for initially setting the drill in the chuck. The chuck construction 152 for supporting the drill is particularly shown in FIGURES 4, 7, 8, 9 and 10. The chuck construction is inclusive of two parallel jaws 186- and 187 respectively provided with V-shaped opposed recesses 188 to accommodate a drill D.

As shown in FIGURES 9 and 10, the opposed exterior walls of the jaw member 186 are formed with recesses to accommodate the leg portions 190 of a U-shaped member 192, the leg portions 196' being secured to the chuck jaw 186 by rivets 194. The chuck jaw 187 is also formed with recesses to accommodate the leg portions 190, the jaw 187 being slidable transversely of the chuck jaw 136 so that the jaws may accommodate drills of various sizes. An opening in bight portion of member 192 accommodates a locking screw 1% provided with a knurled knob 197. The screw 1% may be drawn up to clamp the drill D between the chuck jaws 186 and 187.

With particular reference to FIGURE 10, it will be seen that the forward extremities or regions of the chuck jaws 136 and 187 are tapered or in generally convergent relation and that the tapered portions are provided lWltil pairs of V-shaped grooves 200 and 29 1. As shown in FIGURE 4, the gaging fixture 154 is provided with a pair of plates 2% secured thereto by means of rivets 266. As shown in FIGURE 5, the plates 2% are provided with angular edge regions 29% which selectively accommodate pairs of V-sh-aped grooves 2th or 2tl1 formed in the chuck jaws 186 and 187.

The assembly comprising the chuck jaws 186, 187, the U-shaped member 192 and the drill D to be ground is temporarily mounted between the plates 2% of the fixture 154 for positioning the drill in contact with the surface 1'51) of the gage block 147.

The holder for accommodating the chuck construction and the drill carried thereby during grinding operations is illustrated at 184 in FIGURES 7 and 10. Secured to the sector 170 is a plate 219 which is disposed in a rectangularly shaped recess formed in a handle member 212, the plate 211 being retained in the handle 212 by a cover plate 214 secured to the handle 212.

Mounted upon the portion of the plate 216' extending forwardly of the handle 212 is a supporting means or plate 216 for directly engaging and supporting the chuck jaw construction 152. The distal end region of the plate 216 is provided with upwardly-extending convergentlyarranged blocks or abutments 218 formed with angularly arranged surfaces 220. When the chuck construction 152 shown in FIGURE 10 is mounted upon the plate 216 in the manner shown in FIGURE 8, the angular surfaces 229 of projections 218 engage in the convergently arranged recesses 2111 formed in the chuck jaws 186- and 187.

The forward edge region of the plate 214 is formed with a convergently arranged surface 222. The rear end of each chuck jaw 18d and 187 is provided with V-shaped recesses 224 and 226', and, when the chuck 152 is in the position shown in FIGURE 8, the edge 222 of the plate 214 engages in the recesses 224 of the chuck jaws 186 and 187.

The member 210 is formed with a longitudinal bore 230 in which is disposed a cylindrical member 232, the latter being secured in the bore by a pin 234- disposed in aligned openings in the member 232, the handle portion 212 and the cover plate 214- of the handle.

The member 210 is provided with an abutment 236 and an expansive coil spring 238 is disposed between the abutment 236 and the cylindrical member 232 which, through the medium of the connection with the handle 212 by the pin 234, exerts a forwardly acting bias or force upon the handle 212 and cover plate 214 to hold the chuck construction 152 in engagement with the projections 218 through engagement of the forward edge 222 of the plate 214 in the recesses 224 in the chuck jaws. The portion 212 of the handle is provided with a laterally extending hand grip 240 and the member 210 provided with a hand grip or projection 242 as shown in FIGURES 7 and 10.

By grasping the hand grip members 240 and 242 and moving grip member 240 toward grip member 242 the plate 214 is withdrawn from engagement with the chuck jaws 186 and 187 and the spring 238 compressed. The chuck construction 152 may then be inverted so that the recesses 20th engage the pnojections 218 and the angular edge 222 of the plate 214 engages the recesses 226 in the rear ends of the chuck jaws 186 and 187 to secure the drill in :a position 180 removed from its initial position. Through this arrangement both cutting lips or edges of the drill may be ground.

During a grinding operation, with the chuck carrying a drill D illustrated in the position shown in FIGURE 7, the operator, through the medium of the handle 24%, oscillates the holder 184 and the chuck 152, the sector 170 the arcuately shaped member 166 and the shaft 108 about the axis of the shaft designated by the line AA. It will be noted in FIGURES 7 and 8 that the axis AA is slightly above the horizontal plane through the axis of the grinding wheel and slightly forwardly of the wheel surface 92.

The operator oscillates the chuck and drill holder 184 downwardly during a drill grinding or drill pointing operation and, under the influence of the cam follower 138 engaging the variable pitch cam surface the drill is drawn radially of the grinding wheel surface 92 to form the relief areas indicated at 251) on the end of the drill in FIGURES 11 through 14 and to sharp-en the lips or cutting edges 252 of the drill.

An important feature of the construction is the provision of the constant increment gage surface of the gage block 147 for setting the drill in a holder which is correlated with the variable pitch or variable increment cam surface 130 to provide for varying amounts of relief on the end of a drill. The czun follower or roller 138 carried by the shaft 108 is effective, through the medium of the variable pitch surface 130 of the cam 129, to progressively move the drill D into and radially of the wheel during a grinding operation.

Through the variable pitch cam surface 130, the relief angle, in the various positions of adjustment with respect to the drill, will be diiferent for different gage settings of the drill on the gage block 147. If the pitch of the cam were a constant increment, the same amount of relief would be ground on the drill irrespective of its gage setting position in the chuck as determined by its engagement with the gage surface 150 of the gage block 147.

The operation of the apparatus of the invention in grinding the lips or cutting edges and clearance or relief areas on the end of a drill are as follows:

The first step is to mount the drill D between the chuck jaws 186 and 187 of the chuck construction 152 and position the chuck in the fixture 154 for cooperation with the gaging surface 150, the particular setting of which determines the amount of relief clearance which is to be ground upon the drill. The operator backs off the jaw clamping screw 1% and inserts the drill D between the jaws with the end of the drill projecting forwardly of the chuck jaws. The screw 1% is then drawn up lightly until the chuck jaws contact the drill.

The chuck 152 is then positioned in the gaging fixture 154 shown in FIGURES 1, 2 and 4 with the forward converging surfaces of the chuck jaws contacting the convergently arranged surfaces 208 of the plates 264 of the fixture 154. The gage block 147 is then adjusted by rotating the cup-shaped housing 126 relative to the cylindrical housing 1%. For purposes of illustration it will be noted in FIGURE 5 that graduations numbered 1, 2, 3 and 4 are inscribed on the portion 141% of the housing 126 which is rotatable relative to the pin 156.

By rotating the cup-shaped housing 126, the gage block 147 is correspondingly rotated, which changes the relative position of the angularly arranged gaging surface 150 of the block with respect to the drill D. If a minimum amount of relief clearance is to be ground upon the drill, the housing 126 is rotated to bring the index numeral 1 in alignment with the pin 156 which moves the region of the gage surface 150 engaged by the drill further from the drill retaining chuck 152. The maximum relief clearance that may be formed upon a drill point is attained in setting the drill by moving the housing 126 until the graduation identified by numeral 4 is adjacent the pin 156.

While the surface 151? on the gage block 147 is of a constant increment, the cam surface 135 of the cam block 129, which is also concomitantly adjusted with respect to the cam follower 138 when the housing 126 is rotated, is of a variable pitch, and adjustment of the gage block 147 'brings a different range area of the variable cam surface 130 into position to control the cam follower 138 which is effective by moving the shaft 108 lengthwise to impart a particular angle or amount of relief clearance to the end of a drill dependent upon the range area of the variable pitch cam controlling the position of the drill with respect to the grinding wheel during grinding operations.

After the operator has determined the amount or angular relief clearance to be formed on the drill, and the gage block 147 moved to the selected position, the locking screw 158 is drawn up to lock the cup-shaped housing 1-26 to the cylindrical housing 165. The cam block 129 is thus locked against relative movement with the proper range of the variable pitch cam surface 139 in a position to control the follower 138.

The operator then moves the drill D through the chuck jaws 136 and 137 until the point of the drill contacts the gage surface 150 in the manner shown in FIG- URES 4 and 5. The drill is rotated in the chuck jaws so that a cutting lip or edge 252 of the drill is positioned in a vertical plane as shown in FIGURE 5. This setting may be performed by visual alignment of the edge in a vertical plane. The locking screw 1% is then drawn tightly to cause the drill to be gripped or clamped between the chuck jaws 186 and 187.

The manipulating knob 45 is then rotated in a direction to move the carriage 52 so that when the drill chuck 152. is placed in the holder 184-, the end of the drill is spaced from the grinding surface 92 of the grinding wheel. The chuck 152 and the drill D to be ground is then mounted in the holder 184 shown in FIGURES '7, 8 and with the projections 218 on the plate 216 engaging the recesses 251 in the chuck jaws, the hand grip 2 33 drawn rearwardly towards the grip portion 242 to withdraw the plate 214 so as to permit mounting the chuck in contact with the upper surface of the plate 216.

The grip portion 245 is then released and, under the expansive pressure of the spring 238, the portion 212 and the cover plate 214 are moved toward the chuck jaws bringing the angularly arranged edge surface 222 of plate 214 into engagement with the recesses 224 in the rear ends of the chuck jaws 186 and 137. Under the influence of the spring pressure, the chuck 152 is securely held in grinding position in the holder as shown in FIGURES 7 and 8. The sector 176 is adjusted to bring the proper graduation 179 in registration with the index line or edge 1% of member 166 and the setscrew 1'78 drawn up, the setting determining the angle of the cutting edges of the drill with respect to its longitudinal axis.

With the handle 38 carried by the threaded bushing 35 shown .in FIGURES 1 and 3, in engagement with its stop or abutment pin or member 39, the knob 45 is rotated to rotate the screw 40 and move the carriage 32 and the apparatus mounted by the carriage supporting the tool holder 184 axially of the axis of the grinding wheel until the lip of the drill engages the grinding surface 92 of the grinding wheel. The knob 45 is then moved an additional amount to elfect a grinding of the lip of the drill to the extent that it is necesary or desirable to sharpen or grind the lip.

While this adjustment is being made, the operator holds the handle construction 184 in a generally horizontal position. The manipulating knob 64 is rotated to move the crosshead or supplemental carriage 52 in a direction toward the axis of the grinding Wheel so that the center line of the drill will intersect the face of the grinding wheel at a slight distance from the peripheral edge of the wheel surface 92 as indicated in FIGURES 7 and 11.

The grinding of the first lip of the drill and the adjacent relief area is effected by oscillating the holder downwardly and upwardly, which oscillation occurs about the axis A-A of the shaft 168.

At the start of the grinding operation, the center line of the drill is slightly inside the peripheral edge of the wheel. The angular extent of oscillatory movements of the holder 134 to effect a complete grinding of a lip and its adjacent relief area is about 60. The relative position of the drill with respect to the grinding wheel at the start of a grinding operation on a lip of the drill is indicated in FIGURE 12 and position (1) in FIGURE 11. As the handle 184 is moved downwardly the position of the drill is shifted as indicated in FIGURE 13 and position (2) in FTGURE 11, and during such movement the shaft 1% is under the influence of the cam surface 135 and follower 133, the drill is retracted generally radially away from the wheel, the drill being in the position shown in FIGURE 13.

Upon further downward movement of the holder 184 at about an angle of 60 from its initial position, the relative position of the drill is indicated in FIGURE 14- and, in such position, the center line of the drill is outside of the peripheral edge of the grinding wheel as schematically indicated at position (3) in FIGURE 11.

The angularity of the clearance or relief on the drill is controlled by the selected range of the variable pitch cam surface 130, its position being determined by the position of the cam block at the time the drill is set or positioned in the chuck jaws by engagement of the drill with the constant increment gage surface 15s on the gage block 147.

After the first lip of the drill and its adjacent relief area are ground upon the wheel, the operator moves the handle construction 18 to substantially horizontal position and grasps the handle 38 shown in FIGURE 1 moving the same to a vertical position, which action rotates the threaded bushing 36 so as to move the carriages 32 and 52 slightly forwardly of the base 15 and grinding wheel 80 thereby Withdrawing the drill from engagement with the grinding wheel surface Q2.

The operator then grasps the handle or grip portions 240 and 242 retracting the grip 2411, the plate 214 and member 212 to disengage the angular surface 222 of the plate from the chuck jaws. The chuck 152 is then inverted and the recesses 20% engaged with the projections 218 and the plate 214 released whereby the biasing force of spring 238 moves the plate 214 so that the edge thereof engages the recesses 226 in the chuck jaws 186 and 187. This inversion of the chuck rotates the drill and places the second lip thereof in a position to be ground.

The operator then moves the handle 38 downwardly until it engages the stop member 39, this action bringing the second cutting edge or lip of the drill into contact with the grinding wheel face 92 and is ground to the same extent that the first lip of the drill was ground as previously described. The operator then oscillates the handle construction 18 1 through its downward movement of approximately 60 and back to horizontal position to eifect a grinding of the second relief area on the drill point. It should be noted that this operation requires no adjustment or readjustment of the grinding apparatus other'than movement of the handle 63 to withdraw the drill from engagement with the grinding wheel during reversal of the drill chuck 152.

Through the provision of the drill setting gage oriented with the variable pitch cam surface 130, the initial setting of the drill with respect to the fixture and gage surface determines the effective amount of sweep movement for a particulra amount of relief formed on the drill. When the drill is initially positioned at its greatest distance from the holder or fixture 15 1, the least relief angle is 9 formed on the drill, as it is moved through an arc of greater radius during the grinding operation.

When increased angle of relief is desired, the drill is positioned in the chuck with the setting gage so that the drill is at a shorter distance from its gage fixture and holder so that, during a grinding operation, it is moved through a more acute curve or are which imparts a greater angularity of relief clearance to the drill.

An important feature of the arrangement resides in the correlation of the movement of the cam block 129 with the gage block '147 so that there is a predetermined relationship at all times between the variable contour or pitch of the cam surface 134) and the gage block 147.

This predetermined relationship assures the positioning of the drill in the chuck so that the end of the drill will always be brought into proper cutting engagement with the face 92 of the grinding wheel. Such arrangement further assures that the center line of the drill during a grinding operation, irrespective of the angle of relief clearance which is to be formed on the drill, will initially intersect the face of the drill the same distance from the peripheral edge of the wheel. For grinding different size drills, chuck jaws 186 and 187 may be provided adapted to accommodate various ranges of drill sizes.

When it is desired to dress the grinding face 92 of the grinding wheel, the operator manipulates the knob 45 to retract the carriage 32 and the sector 170 a sufiicient distance forwardly of the apparatus to enable the operator to grasp the handle 99 shown in FIGURE 1 to swing the member 98 upwardly bringing the truing diamond 102 across the face of the grinding wheel to true the same. The adjustment of the truing diamond holder is accom plished by rotating the knob 45 to move the carriage 32 along an axis parallel with the axis of the grinding wheel the required amount to engage the truing diamond with the wheel.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

1. Apparatus for grinding twist drills including, in co-m bination, a support, a carriage adjustably mounted on said support, an arbor supporting a grinding wheel, a motor for rotating the arbor and grinding wheel, a shaft mounted by the carriage arranged for rotational and axial movements relative to said carriage, a drill mounting chuck, a holder for said chuck, a member movable with said shaft formed with an arcuately shaped recess, an arcuately shaped arm extending into said recess for supporting said holder and chuck, and cam and cam follower means associated with said shaft for effecting lengthwise movement of said shaft concomitantly with rotational movement of said shaft and arm during a grinding operation whereby to grind relief clearance on the drill.

2. Apparatus for grinding twist drills including, in combination, a support, a carriage adjustably mounted on said support, an arbor supporting a grinding wheel, a motor for rotating the arbor and grinding wheel, a shaft mounted by the carriage arranged for rotational and axial movements relative to said carriage, a drill mounting chuck, a holder for said chuck, a member movable with said shaft formed with an arcuately shaped recess, an arcuately shaped arm adjustably mounted in said arcuately shaped recess in said member and sup; porting said holder and chuck, cam and cam follower means associated with said shaft for effecting lengthwise movement of said shaft concomitantly with rotational movement thereof during a grinding operation whereby to grind relief clearance on a drill, and means for modifying the region of engagement of the cam follower means with the cam means to vary the character of the relief clearance ground on a drill.

3. Apparatus for grinding twist drills including, in

combination, a support, a carriage adjustably mounted on said support, an arbor supporting a grinding wheel, a motorfor rotating the arbor and grinding wheel, a shaft mounted by the carriage arranged for rotational and axial movements relative to said carriage, a drill supporting chuck, a holder for said chuck, a member movable with said shaft, means carried by said member for supporting said holder, said chuck and drill to be ground, cam and cam follower means associated with said shaft for effecting lengthwise movement of said shaft concomitantly with rotational movement thereof during a grinding operation whereby to grind relief clearance on a drill, and gage means connected with said cam means and arranged to position the drill in the chuck, said cam means and gage means being adjustable relative to said cam follower means for controlling the angularity of relief clearance to be ground on a drill.

4. Apparatus for grinding twist drills including, in combination, a support, a carriage adjustably mounted on said support, a grinding wheel, a motor for rotating the grinding wheel, an element supported on said carriage, a shaft journaled on said element, a cam member, a cam follower member, one of said members being movable with the shaft, means carried by said element connected with said other member and adjustable relative to said shaft for changing the initial relative position of one of said members with respect to the other, a holder for mounting a drill to be ground, and an element formed with an arcuately shaped recess mounted by said shaft, an arcuately shaped arm extending into said recess and arranged to support said holder and movable about the axis of said shaft whereby the drill during contact with the grinding wheel is rotated about the axis of said shaft and movable lengthwise of said shaft under the influence of the cam and follower members for grinding relief clearance on the drill, said arcuately shaped arm being adjustable relative to the axis of said shaft.

5. Apparatus for grinding twist drills including, in combination, a base, a carriage adjustably supported on said base, a grinding wheel, a motor for rotating the grinding wheel, an element having a tubular portion supported on said carriage, a shaft journaled in the tubular portion of said element, a cam member, a cam follower member, one of said members being movable with the shaft, resilient means biasing the cam member and cam follower member in engaging relation, means carried by said element connected with said other member and adjustable relative to said shaft for changing the initial relative position of one of said members with respect to the other, a holder for mounting a drill to be ground, an arcuately shaped arm mounted by said shaft arranged to support said holder and movable about the axis of said shaft whereby the drill is rotated about the axis of said shaft and movable lengthwise of said shaft under the influence of the cam and follower members during a drill grinding operation, said arcuately shaped arm being adjustable relative to the axis of said shaft.

6. Apparatus for grinding twist drills including, in

combination, a base, a carriage adjustably supported on said base, a grinding wheel, a motor for rotating the grinding wheel, an element supported on said carriage, a shaft journaled on said element, a cam member provided with a variable pitch cam surface, a cam follower member, one of said members being movable with the shaft, means carried by said element connected with said l l shaped arm being adjustable relative to the axis of said shaft.

7. Apparatus for grinding twist drills including, in combination, a support, a carriage adjustably mounted on said support, an arbor supporting a grinding Wheel, a motor for rotating the arbor and grinding wheel, a shaft mounted by the carriage arranged for rotational and axial movements relative to said carriage, a drill mounting chuck, a holder for said chuck, a member movable with said shaft, means carried by said member for supporting said holder and chuck during a grinding operation, a fixture mounted by the carriage adapted to receive the chuck and a drill mounted therein, gage means for predetermining the position of the drill in the chuck, means supporting said gage means and being adjustable relative to said shaft, cam means provided with a variable pitch cam surface movable with said gage means, and a cam follower mounted by said shaft and cooperating with the cam surface for effecting lengthwise movement of said shaft during rotational movement thereof for controlling the position of the drill relative to the grinding wheel during a grinding operation.

8. Apparatus for grinding twist drills including, in combination, a support, a carriage adjustably mounted on said support, an arbor supporting a grinding wheel, a motor for rotating the arbor and grinding wheel, a shaft mounted by the carriage arranged for rotational and axial movements relative to said carriage, a drill mounting chuck, a holder for said chuck, a member movable with said shaft, means carried by said member for supporting said holder and chuck during a grinding operation, a fixture mounted by the carriage adapted to receive the chuck and a drill mounted therein, a gage block having a gaging surface, means supporting said gage block and being adjustable relative to said shaft, cam means provided with a variable pitch cam surface movable with said gage block, a cam follower mounted by said shaft and cooperating with the cam surface for effecting lengthwise movement of said shaft during rotational movement thereof for controlling the position of the drill relative to the grinding wheel during a grinding operation, and means maintaining said cam follower in engaging relation with the cam surface of the cam means.

9. Apparatus for grinding twist drills including, in combination, a support, a carriage adjustably mounted on the support, a rotatable grinding wheel, a motor for rotating the grinding wheel, a first member mounted by the carriage for rotational and axial movements, a holder for mounting a drill to be ground, means connected With the first member formed with an arcuately shaped recess,

an arcuately shaped arm adjustably mounted in said recess for supporting the holder during a drill grinding operation, a second member mounted for adjustment relative to said first member, cam means provided with a variable pitch cam surface connected with one of said members, a cam follower arranged for cooperation with the cam surface connected with the other of said members, and means for adjusting the initial relation of the cam surface with the cam follower for controlling the axial movement of said first member to effect the grinding of varying angles of relief clearance on a drill.

10. Apparatus for grinding twist drills including, in combination, a support, a carriage adjustably mounted on the support, a rotatable grinding wheel, a motor for rotating the grinding Wheel, a shaft mounted by the carriage for rotational and axial movements, a holder for mounting a drill to be ground, means connected with the shaft for supporting the holder during a drill grinding fl operation, a'cup-shaped member mounted for rotational adjustment relative to said shaft, cam means provided with a variable pitch cam surface connected with said cup-shaped member, a cam follower mounted by the shaft arranged for cooperation with the cam surface, and gage means for determining the initial relation of the cam surface with the cam follower for controlling the axial movement of said shaft to effect the grinding of varying angles of relief clearance on a drill.

11. Apparatus for grinding twist drills including, in combination, a base housing, a grinding wheel journally mounted by the housing, a motor for rotating the grinding wheel, a first carriage supported on said housing and adjustable along an axis parallel with the axis of rotation of the grinding wheel, a second carriage mounted on said first carriage and adjustable along an axis substantially normal to the axis of the grinding wheel, a shaft mounted for oscillatory and axial movement on said second carriage, a member arranged for adjustment about the axis of the shaft, means having a variable pitch cam surface movable with said member, a cam follower carried by said shaft cooperating with the variable pitch cam surface, an arcuately shaped arm, means connected with the shaft supporting said arm, said arm being adjustable in an are relative to said shaft, a drill mounting holder removably supported on said arm and arranged to move the drill relative to the grinding wheel during a drill grinding operation, the lengthwise movement of said shaft being controlled by said cam surface for determining the character of relief clearance ground on a drill.

12. Apparatus for grinding twist drills including, in combination, a base housing, a grinding wheel journally mounted by the housing, a motor for rotating the grinding wheel, a first carriage supported on said housing and adjustable along an axis parallel with the axis of rotation of the grinding wheel, a second carriage mounted on said first carriage and adjustable along an axis substantially normal to the axis of the grinding wheel, a shaft mounted for oscillatory and axial movement on said second carriage, a member arranged for adjustment about the axis of the shaft, a gage block having a constant increment gaging surface mounted on said member, means having a variable pitch cam surface movable with said member and gage block, a gaging fixture mounted on said second carriage arranged to support a drill mounting chuck to predetermine the position of the drill in the chuck by the constant increment gaging surface, a cam follower carried by said shaft cooperating with the variable pitch cam surface, a drill chuck holder, means connected with the shaft supporting the drill chuck holder arranged to move the drill relative to the grinding wheel during a drill grinding operation, the lengthwise movement of said shaft being controlled by said cam surface for determining the angle of relief clearance ground on a drill.

13. Apparatus for grinding twist drills including, in combination, a base housing, a grinding Wheel journaled on the housing, a motor for rotating the grinding wheel, a first carriage supported on said housing and adjustable along an axis parallel with the axis of rotation of the grinding wheel, a second carriage mounted on said first carriage and adjustable along an axis substantially normal to the axis of the grindnig wheel, a shaft mounted for oscillatory and axial movement onsaid second carriage, a member arranged for adjustment about the axis of the shaft, a gage block having a constant increment gaging surface mounted on said member, a cam block having a variable pitch cam surface movable with said member and gage block, means for locking said member in adjusted position, a gaging fixture mounted on said second carriage arranged to support a drill mounting chuck to predetermine the position of the drill in the chuck by the constant increment gaging surface, a cam follower carried by said shaft cooperating with the variable pitch cam surface, an arcuately shaped arm, means connected with the shaft supporting the arm, said arm being adjustable in an are relative to said shaft, a drill chuck holder removably supported on said arm and arranged to move the drill relative to the grinding wheel during a drill grinding operation, the lengthwise movement of said shaft being controlled by said cam surface for determining the angle of relief clearance ground on a drill.

14. Apparatus for grinding twist drills including, in combination, a base housing, a grinding wheel mounted by the housing, a motor for rotating the grinding wheel, a first carriage supported on said housing and adjustable along an axis parallel with the axis of rotation of the grinding wheel, a second carriage mounted on said first carriage and adjustable along an axis substantially normal to the axis of the grinding wheel, a shaft mounted for oscillatory and axial movement on said second carriage, a member arranged for adjustment about the axis of'the shaft, a gage block having a constant increment gaging surface mounted on said member, means having a variable pitch cam surface movable with said member and gage block, a gaging fixture mounted on said second carriage arranged to support a drill mounting chuck to predetermine the position of the drill in the chuck by the constant increment gaging surface, a cam follower carried by said shaft cooperating with the variable pitch cam surface, spring means biasing the cam follower into constant engagement with the cam surface, an arcuately shaped arm, means connected with the shaft supporting the arm, said arm being adjustable in an are relative to said shaft, a drill chuck holder removably supported on said arm and arranged to move the drill relative to the grinding wheel during a drill grinding operation, the lengthwise movement of said shaft being controlled by said cam surface for determining the angle of relief clearance ground on a drill.

References Cited in the file of this patent UNITED STATES PATENTS 2,363,482 Clarke Nov. 28, 1944 2,598,055 Hogfors May 27, 1952 2,632,983 Kapnick Mar. 31, 1953 2,785,510 Garrison Mar. 19, 1957 2,866,302 Amiet Dec. 30, 1958 2,958,167 Mueller Nov. 1, 1960 2,972,839 Erdelyi Feb. 28, 1961 

1. APPARATUS FOR GRINDING TWIST DRILLS INCLUDING, IN COMBINATION, A SUPPORT, A CARRIAGE ADJUSTABLY MOUNTED ON SAID SUPPORT, AN ARBOR SUPPORTING A GRINDING WHEEL, A MOTOR FOR ROTATING THE ARBOR AND GRINDING WHEEL, A SHAFT MOUNTED BY THE CARRIAGE ARRANGED FOR ROTATIONAL AND AXIAL MOVEMENTS RELATIVE TO SAID CARRIAGE, A DRILL MOUNTING CHUCK, A HOLDER FOR SAID CHUCK, A MEMBER MOVABLE WITH SAID SHAFT FORMED WITH AN ARCUATELY SHAPED RECESS, AN ARCUATELY SHAPED ARM EXTENDING INTO SAID RECESS FOR SUPPORTING SAID HOLDER AND CHUCK, AND CAM AND CAM FOLLOWER MEANS ASSOCIATED WITH SAID SHAFT FOR EFFECTING LENGTHWISE MOVEMENT OF SAID SHAFT CONCOMITANTLY WITH ROTATIONAL MOVEMENT OF SAID SHAFT AND ARM DURING A GRINDING OPERATION WHEREBY TO GRIND RELIEF CLEARANCE ON THE DRILL. 